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<table width="100%" summary="page for glymet"><tr><td>glymet</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Glyphosate and metsulfuron-methyl tested on algae.</h2>

<h3>Description</h3>

<p>The dataset has 7 mixtures, 8 dilutions, two replicates and 5 common control controls. 
Four observations are missing, giving a total of 113 observations.
</p>


<h3>Usage</h3>

<pre>data(glymet)</pre>


<h3>Format</h3>

<p>A data frame with 113 observations on the following 3 variables.
</p>

<dl>
<dt><code>dose</code></dt><dd><p>a numeric vector of dose values</p>
</dd>
<dt><code>pct</code></dt><dd><p>a numeric vector denoting the grouping according to the mixtures percentages</p>
</dd>
<dt><code>rgr</code></dt><dd><p>a numeric vector of response values (relative growth rates)</p>
</dd>
</dl>



<h3>Details</h3>

<p>The dataset is analysed in Soerensen et al (2007). 
The concentration addition model can be entertained for this dataset.
</p>


<h3>Source</h3>

<p>The dataset is kindly provided by Nina Cedergreen, Department of Agricultural Sciences, 
Royal Veterinary and Agricultural University, Denmark.
</p>


<h3>References</h3>

<p>Soerensen, H. and Cedergreen, N. and Skovgaard, I. M. and Streibig, J. C. (2007) 
An isobole-based statistical model and test for synergism/antagonism in binary mixture toxicity experiments, 
<em>Environmental and Ecological Statistics</em>, <b>14</b>, 383&ndash;397.
</p>


<h3>Examples</h3>

<pre>


## Fitting the model with freely varying ED50 values
glymet.free &lt;- drm(rgr~dose, pct, data = glymet, 
fct = LL.3(), pmodels = list(~factor(pct) , ~1, ~factor(pct))) 

## Lack-of-fit test
modelFit(glymet.free)  # acceptable
summary(glymet.free)

## Plotting isobole structure
isobole(glymet.free, exchange=0.01)

## Fitting the concentration addition model
glymet.ca &lt;- mixture(glymet.free, model = "CA")

## Comparing to model with freely varying e parameter
anova(glymet.ca, glymet.free)  # borderline accepted

## Plotting isobole based on concentration addition
isobole(glymet.free, glymet.ca, exchange = 0.01)  # acceptable fit

## Fitting the Hewlett model
glymet.hew &lt;- mixture(glymet.free, model = "Hewlett")

### Comparing to model with freely varying e parameter
anova(glymet.ca, glymet.hew)  
# borderline accepted
# the Hewlett model offers no improvement over concentration addition

## Plotting isobole based on the Hewlett model
isobole(glymet.free, glymet.hew, exchange = 0.01)  
# no improvement over concentration addition

</pre>


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